You were so good all week. But then you snuck a donut...and then another. To get back on track quickly, start here.

There's that dreaded point in every diet — for me, it's after the first 10 pounds — when you start to slack off a little. You skip lunch one Saturday, and later that night at a restaurant with your husband, you're so ravenous that you order the salad, the soup, the entrée, and two glasses of chardonnay. Uh-oh, you think, I've blown it. And then you really blow it — by sampling half the dessert cart.

To avoid facing the bad news, you go incommunicado with your scale. Feeling defeated, you begin to slack off even more and, before you know it, those 10 pounds are back. Now you have to muster the motivation to lose that stubborn weight all over again.

Can you say yo-yo dieting? It's a cycle, but it's not unbreakable. The first step toward success: Learn how to deal with setbacks. "I always tell people to 'fail fast' — the idea is to recognize your error but avoid wallowing in it," says Holly Wyatt, M.D., who's with the National Weight Control Registry (NWCR). "One mistake isn't going to reverse everything you've worked for." Here, Dr. Wyatt and other weight-loss experts offer quick fixes for seven common diet goofs, plus tips on how to avoid future slipups.

"I skipped breakfast"

Maybe you were in a hurry. Maybe you thought you could cut some calories. But now it's 11 a.m., and you haven't eaten anything for 15 hours straight. You're so famished, you can't decide whether to buy a bear claw at the bakery, steal candy from your coworker's stash, or wait until lunch so you can pig out at your favorite Chinese restaurant. "Breakfast is a must," says Dr. Wyatt. "Otherwise, you'll end up wanting to eat everything you see." A survey from NWCR, which tracks more than 5,000 people who have kept off at least 30 pounds for a year or longer, found that 78 percent of participants have a meal every single morning.

Fast Fix

Eat something, but resist the junk food. You'll stay fuller longer if you have fruit, low-fat yogurt, or string cheese. An energy bar will also do the trick. But make sure you find one that has staying power — that means at least 3 grams of fiber, 8 grams of protein, and less than 250 calories. Two of our favorites: Clif's Mojo Fruit Nut Crunch Bar and PowerBar Nut Naturals.

Next Time

Make breakfast simple. To guarantee you never skip this meal again, keep a week's worth of easy eats in the house. A few good picks (which you can also stash at the office for midday munchies): single-serve instant oatmeal (McCann's Instant Irish Oatmeal has three sugar-free varieties — apple and cinnamon, maple and brown sugar, and cinnamon roll); low-fat granola, which you can mix with plain yogurt; and single-serving cans of light fruit (like Del Monte's no-sugar-added pear chunks, only 40 calories). But beware of so-called breakfast bars, which are often packed with sugar. Make sure you read the labels carefully before you buy.

Eat every four hours during the day. That's about how much time it takes for hunger to return after a meal, says Madelyn Fernstrom, Ph.D., director of the Weight Management Center at the University of Pittsburgh Medical Center. You'll do far less damage if you have a small snack mid-morning and in the afternoon than if you try to assuage your gnawing hunger at mealtimes, when the plates, portions, and your appetite are all bigger.

Most of us don't dance on the table after a few Long Island Iced Teas — we eat everything on it. Why? The body doesn't register liquid calories, so even if you drink 500 of them, you'll still crave food. When Pennsylvania State University researchers gave people a caloric drink (such as fruit juice, sweetened soda, or even milk) with a meal, the participants didn't consume any less food when they sat down to eat. And neither did you — so now you have all the alcohol calories to burn off, as well as a huge dinner.

Fast Fix

Get some exercise. Taking a walk or a bike ride will shift your mind-set from I am a colossal boob to I'm back in the game! A reminder from Dr. Wyatt: "You haven't failed unless you continue the counterproductive behavior."

Advertisement - Continue Reading Below

Next Time

"Never drink on an empty stomach," says Timothy Harlan, M.D., a chef-turned-physician who also appears on the Food Network's Cooking Thin. At parties, grab a handful of nuts (they're satisfying and healthy) before you pick up a wineglass. If you're out to dinner, try to "sip your wine slowly until the salad is served," Dr. Harlan adds. (And no, this is not an excuse to hit the bread basket...wait for something healthier to arrive.)

Pace yourself. "In calories, one Long Island Iced Tea is the equivalent of 26 fat-fried onion rings," says Elizabeth Somer, R.D., author of 10 Habits That Mess Up a Woman's Diet. So make sure you drink water or seltzer — both zero calories — in between alcoholic drinks. Some numbers to keep in mind while you sip: A 5-ounce glass of wine is around 125 calories; beer is about 65 calories. A 1.5-ounce shot of alcohol (for, say, Scotch or vodka on the rocks) is about 95 calories. A 3-ounce margarita, about 170 calories. A 2.5-ounce martini, 175 calories.

More From Good Housekeeping

"I ate a supersize fast-food meal"

Hitting the drive-through at Burger King once isn't such a big deal — the problem is that if you do it one time, you're much more likely to swing by again. And that's when the pounds really start to pile on. A 15-year study led by researchers at the University of Minnesota showed that people who ate fast food more than twice a week gained 10 more pounds than participants who had it less than once a week. There were also health ramifications: The drive-through frequenters had a higher risk of diabetes.

Fast Fix

Savor your indulgence. "Splurges do happen," says Dr. Harlan. "For some of us, it's fast food; for others, it's a big chocolate bar." The trick is to focus on each and every bite — this is a treat, one you won't be having tomorrow, so take the time to really enjoy it.

Next Time

Order low-cal. If you must hit the drive-through, choose foods that won't do major diet damage. At Burger King, for example, choose the Whopper Jr. (290 calories with no mayo) instead of the regular Whopper (670 calories). And always skip the fries: A small bag at McDonald's clocks in at 250 calories, about half of which is fat. Instead, order the side salad (20 calories) with a packet of Newman's Own Low Fat Balsamic Vinaigrette (40 calories). For more good eats at fast-food joints, check out Dr. Harlan's Website, drgourmet.com.

Don't skip supper to compensate. That kind of starvation strategy always backfires, warns Fernstrom. "The day after your severe restriction, you'll be eating everything, including the paint off the walls."

That's understandable — but it will cost you big time. "You don't realize how much mindless eating you do every day," says Somer. "You taste what you're cooking, or grab a french fry, or eat the rest of your kid's cake at a birthday party. On average, there's probably 25 calories in each of those mouthfuls. If you take just four mindless bites a day, that adds up to an extra pound every month."

Fast Fix

Buy a little notebook. By writing down every sip and nibble, you'll avoid surprise weight gains. If carrying a notebook is too yesterday, go the electronic route. Sites such as nutrihand.com offer free subscriptions that allow you to track your meals. Or you can use a pocket-size food diary, such as CalorieSmart ($69, coheso.com).

Next Time

Measure everything. Most of us have trouble eyeballing a cup or a 4-ounce serving with any accuracy — dietitians call this portion distortion. So for a few days, measure and weigh all your food. Here's one shortcut: "Ask the butcher to divide the meat you buy into 4-ounce servings, which will shrink down to about 3 ounces when you cook it," suggests Somer. "Buy individual 4-ounce potatoes instead of a whole bag. And use measuring cups and spoons until you become very accustomed to what a cup or a tablespoon looks like."

"I'm eating lots of low-fat foods"

And you're not losing any weight, right? There's a reason why. "Research shows that if you tell a person that a food is low-fat, she'll take a larger serving," says Somer. And more food — even if it's nonfat — means more calories.

Fast Fix

Read labels carefully. The front of the package can make all kinds of cheerful claims ("Half the fat!"), but the cold facts are in the nutrition information. You'll find, for example, that those delicious SnackWell's Fat Free Devil's Food Cookies are 50 calories each. (So you might want to put that second one down.) And those low-fat Cheez-Its? Sure, they're only 130 calories a serving. But that's just 29 measly crackers — you can eat that in one minute alone.

Next Time

Eat your greens. Veggies are low in calories and also extra filling. A study from Pennsylvania State University showed that women who ate a large low-cal salad (lettuce, carrots, celery, tomatoes, and cucumber tossed with fat-free dressing and light cheese) before lunch felt so full, they ate less at the meal.

Let yourself have the low-cal dressing. It won't throw off your numbers, and it may encourage you to eat more of these salad superfoods.

You kicked your walking shoes under the bed, threw a blanket over your treadmill, and are driving the long route to work so you don't have to see all the walkers in your neighborhood. We understand — it's hard to get motivated after you've missed a few days of exercise. But those skipped days can easily turn into weeks, so it's important to start up again fast. Here's the good news: "Fitness is the one thing that comes back pretty quickly," says Fernstrom. "By the end of a month, you should be close to where you were before."

Fast Fix

"Go out and walk for 10 minutes," advises Dr. Wyatt. "And tell yourself you can stop at that point if you want. Yes, you might quit in 10 minutes. But once you're out on the sidewalk, you'll probably keep walking.

Next Time

Buddy up. "If you have an exercise partner, it's easier to stay committed," says Dr. Wyatt. So enlist a friend to walk with you every day. Short on buddies? Visit walkers.meetup.com to find folks in your area.

Find a fun exercise. "If your workout is drudgery, you won't do it," says Fernstrom. So if you've worn out the treadmill at the gym, take an aerobics class instead. Or try these fun alternatives (they all burn more calories per hour than walking): ballet or swimming laps (422), biking or playing Ping-Pong (281).

"I haven't weighed myself all week"

If you know the news will be bad, who can blame you? But that's just the time to step on the scale. Once you know the worst, you can act before a few extra pounds become 10.

Fast Fix

Change your attitude toward the scale. Think of it as your own personal coach, suggests Dr. Wyatt. And it really does help fight fat: Of the NWCR participants, more than 60 percent weighed themselves daily to keep pounds from creeping back on.

Next Time

Stop kidding yourself. Avoiding the scale is just another form of denial. "Refusing to acknowledge that there's a problem just makes it worse," says Dr. Wyatt.

Don't get number obsessed. If you were as good as gold all week but still gained a little, don't flip out. Some of it might be water weight — last night's moo shu pork, the salty bag of popcorn you ate at midnight, or even your menstrual cycle.

Don't take weight gain personally. A lot of us have an annoying habit of tying our weight to our self-esteem. But the number on your scale is just information. "Weighing yourself is like monitoring your blood pressure or blood sugar," says Dr. Wyatt. "It lets you know where you are — not what kind of person you are."